During the operation of a marine diesel engine, the circulating lubricant generally becomes contaminated with water. The effective working life of the lubricant is limited by the accumulation of water, which, apart from altering the lubricant properties of the oil, may have a deleterious effect on the metal to be lubricated. Similar considerations arise with other uses of oils.
In order to determine whether the oil is suitable for further use of for regeneration or rejection, it is frequently necessary to know whether water is present in the oil in excess of a predetermined tolerated proportion. Such a proportion might be in the region of a few percent, e.g. 1 to 5 percent by weight of wet lubricant, but substantially higher water contents can be encountered. On the other hand, it may be desired to apply a more stringent standard, of a fraction of one percent.
In my co-pending application Ser. No. 796,107 (now U.S. Pat. No. 4,089,652) I have disclosed an improved method for providing a direct indication of the water content of an oil sample. The method, employing a simple form of apparatus can be used by unskilled operators and is capable of producing good results even when the water is present in a highly emulsified state in the oil.
The method comprises bringing a sample of the oil which is to be tested into contact with a reagent which is chemically inert to the oil but reactive with the water in the oil to produce a gas. The reagent is present in an inert liquid such as kerosine which is miscible with the oil sample. The pressure generated by the evolved gas is used to drive the inert liquid into a collector in which the amount expelled by the gas pressure can be estimated visually, either to obtain a numerical estimate of the water content or to determine whether the oil contains less or more than a predetermined amount of water.